Day: August 31, 2012

[Jerry] missed the laser cutters he had been using at the local TechShop. It closed down and after seeing some hardware in a surplus store he decided to build a laser cutter to call his own. You won’t be disappointed by his build log. It’s got a ton of hi-res images and plenty of explanation.

Often, cost is the key consideration in these types of builds. [Jerry] spent a little more than average, but look what he got back out of it. This started as a CNC machine aimed at loading silicon wafers for a company making electron microscopes. It’s barely been used, and the light-duty specs will work just fine with a laser cutter as the gantry won’t be moving much weight or fighting the rotational force of a mill motor. He tore out the stock controllers and built his own, adding a q-switched 355nm Frequency Tripled DPSS laser along the way. We’re not quite sure what that means… but in laymen’s terms it’s an ultraviolet laser source. See the finished unit cutting out some Kapton in the clip after the break.

As you can see, launching an RC airplane off of a hotel balcony is easy. But watch the video and you’ll find out trying to fly through the french doors for a landing is another story. [Team BlackSheep] hits (har, har) Thailand in this collection of breathtaking flights.

The system is based on two curved and inclined pipes which make up the rails of the system. The dolly that rides along the rails has a geared motor on it which turns at 2 RPM. This is used as a winch, spooling a string that is tied to the high-end of the rail system. As the winch winds the string, the dolly slowly moves along the track.

To make this work over multiple days they covered all of the windows in foil and lighted the room with fluorescent fixtures. An intervalometer was used to trigger the camera every three minutes. An Arduino monitors the camera’s shutter LED via a light dependent resistor. Sixty seconds after an image is take the Arduino will drive the dolly motor for a few seconds

The finished video, as well as a hardware show-and-tell, can be seen after the break.

Texas Instruments just open preorders for the new Stellaris LaunchPad. The boards won’t ship until the end of September, but if you don’t mind the wait you can get one for $4.99 including delivery (we’d wager non-U.S. addresses have to pay for delivery, but leave a comment if you know for sure several readers have reported that international shipping is free).

We routinely pay more in shipping for parts orders so we already jumped at the opportunity and put in our own order. Earlier in the month we heard the first murmurs about the device. We’re glad to see they hit the $4.99 target price, but the TI website mentions that this is a promotional price that will be available for a limited time only. The board boasts an ARM Cortex-M4 processor, the Stellaris LM4F120H5QR. It includes 256 KB of flash memory, 32 KB of SRAM, and more peripherals than you can shake a stick at. To get you up and running quickly they’ve included two user buttons and an RGB LED. As with the 16-bit Launchpad, the board acts as its own programmer. It has a microUSB jack, but they’ve included a micro B to USB A cable in the kit to make sure you don’t need to also put in a cable order.

We’ll give a follow-up post once we finally get our hands on the board. We hope this will be easy to get working with a Linux box!

We thought that connecting an Arduino to a Raspberry Pi was overkill, but one thing caught our attention. [Jan Stevens] mentions that the RPi is less expensive than the Ethernet Shield. Interesting. As we looked into his writeup a bit more we began to think he’s onto something. [Jan] uses the PHP serial class to communicate between the RPi and Arduino. This ends up being a very inexpensive way to bring some of the more powerful web programming options to your hardware devices.

Just a few weeks ago we were wondering if we’d try to build our own prosthesis if we were ever to lose a limb. This pair of hacks answers that query with a resounding “YES!”.

To the right is a replacement pointer finger. The missing digit took the first two knuckles with it, but there’s enough left to easily interface with this creation. It’s a mechanically clever assembly that moves as you would expect the original to. See for yourself after the break. It seem the maker intended to mold silicone around the structure but never got around to posting an update video.

On the left we have a chinese man who lost his arms while fishing. It seems they were using homemade bombs instead of nets and one went off prematurely. Since then he’s constructed several different prosthetic arms, each with its own special purpose. This one has a saw connected to it but these two write ups on the man show images of him using a fork and wielding a hammer.

Here’s a way of transmitting audio that makes it virtually impossible for someone else to listen in. Instead of sending radio waves bouncing all over creation, this uses the focused light of a laser to transmit audio. In the image above you can see the silver cylinder which houses the laser diode. It is focusing the beam on a light dependent resistor to the right which looks almost like a red LED due to the intensity of the light.

The simplicity of this circuit is fascinating. On the receiving end there is no more than the LDR, a 1.5V power source, and a headphone jack. The transmitter is not much more complicated than that. It includes an audio output transformer which boosts the resistance of the audio signal. This increase in resistance ensures that the laser diode modulates enough to affect the LDR on the receiving end. The transmitter uses a 3.3V supply. Check out the video after the break to hear the high quality of audio coming through the setup.